Major determination

The value of the compresjiibility of oil is a function of the amount of dissolved gas, but is in the order of 10 x 10" psi" By comparison, typical water and gas compressibilities are 4x10" psi" and 500 x 10" psi" respectively. Above the bubble point in an oil reservoir the compressibility of the oil is a major determinant of how the pressure declines for a given change in volume (brought about by a withdrawal of reservoir fluid during production). 

Cleaning membranes to restore their efficiency is normal in UF. Food and dairy systems require daily cleaning in any event for hygiene more frequent cleaning is economically intolerable. A few industrial systems operate for six months between cleanings. Cleaning shortens membrane life, and it is often the major determinant of membrane-replacement frequency. 

Most organic compounds are water-insoluble. Notable exceptions are the lower molecular weight alcohols, aldehydes, and ketones, all known to be "polar" molecules. This characteristic is of importance to firefighting because the specific gravity of the compound will then be a major determinant of the suitability of water for the suppression of fires involving the chemical. 

On and off the job, everyone is exposed to a great variety of chemical and physical agents, most of which do no harm under ordinary circumstances, but all of which have the potential for being injurious at some level and under some conditions of exposure. How a material is used is the major determinant of the hazard potential. 

The ingestion dose contributes very little to the dose from a severe reactor accident and is usually not computed. However, the food pathway is a major determinant of bow the exposed area must be treated in the months and years following the accident. If the ground concentration is high, the land may be interdicted from agricultural u.se or grazing. 

It is important, however, not to take this analogy too far. In general, the performance of a piece of hardware, such as a valve, will be much more predictable as a function of its operating conditions than will human performance as a function of the PIFs in a situation. This is partly because human performance is dependent on a considerably larger number of parameters than hardware, and only a subset of these will be accessible to an analyst. In some ways the job of the human reliability specialist can be seen as identifying which PIFs are the major determinants of human reliability in the situation of interest, and which can be manipulated in the most cost-effective manner to minimize error. 

Xiong, H., Bnckwalter, B., Shieh, H.-M., and Hecht, M. H., 1995. Periodicity of polar and nonpolar amino acids is the major determinant of secondary structure in self-assembling oligomeric peptides. Proceedings of the National Academy of Sciences 92 6349—6353. 

The Dunning-Huzinaga type basis sets do not have the restriction of the Pople style basis sets of equal exponents for the s- and p-functions, and they are tlierefore somewhat more flexible, but computationally also more expensive. The major determining factor. 

After considering the Redfield-Ketchum-Richards ratio (see Chapter 10) for C N P consider the analog for sulfur in land and marine biota. What key biochemical species are the major determinants of the C S relationship in biota ... 

While the findings in mice are of interest, it is important to note that there are four known mammalian adenosine receptors and that the pattern of adenosine receptor expression on mast cells (as well as other immime cells and/or structural cells), and the regulation of their expression by such cells (e.g., during inflammatory responses), which can represent major determinants of adenosine responses, vary substantially among species [70-72]. For example, it is thought that adenosine-induced broncho-constriction is mediated by adenosine A1 and A2B receptors in rats and mice, A3 receptors in rats, guinea-pigs and mice, and A2B receptors in humans [72]. 

Since biosynthesis of IMP consumes glycine, glutamine, tetrahydrofolate derivatives, aspartate, and ATP, it is advantageous to regulate purine biosynthesis. The major determinant of the rate of de novo purine nucleotide biosynthesis is the concentration of PRPP, whose pool size depends on its rates of synthesis, utilization, and degradation. The rate of PRPP synthesis depends on the availabihty of ribose 5-phosphate and on the activity of PRPP synthase, an enzyme sensitive to feedback inhibition by AMP, ADP, GMP, and GDP. 

Mature human albumin consists of one polypeptide chain of 585 amino acids and contains 17 disulfide bonds. By the use of proteases, albumin can be subdivided into three domains, which have different functions. Albumin has an ellipsoidal shape, which means that it does not increase the viscosity of the plasma as much as an elongated molecule such as fibrinogen does. Because of its relatively low molecular mass (about 69 kDa) and high concentration, albumin is thought to be responsible for 75-80% of the osmotic pressure of human plasma. Electrophoretic smdies have shown that the plasma of certain humans lacks albumin. These subjects are said to exhibit analbuminemia. One cause of this condition is a mutation that affects spUcing. Subjects with analbuminemia show only moderate edema, despite the fact that albumin is the major determinant of plasma osmotic pressure. It is thought that the amounts of the other plasma proteins increase and compensate for the lack of albumin. 

Roux KH, Taylor KA (2007) AIDS virus envelope spike structure. Curr Opin Struct Biol 17 244-252 Sacktor N, Haughey N, Cutler R, Tamara A, Turchan J, Pardo C, Vargas D, Nath A (2004) Novel markers of oxidative stress in actively progressive HIV dementia. J Neuroimmunol 157 176-184 Samson M, LaRosa G, Libert F, Paindavoine P, Detheux M, Vassart G, Parmentier M (1997) The second extraceUular loop of CCR5 is the major determinant of ligand specificity. J Biol Chem 272 24934-24941... 

The epidemiological evidence suggests that diet is a significant factor in the development of cancer. In their classic epidemiological study, Doll and Peto (1981) estimated that diet was responsible for as many as 35% of cancers in the West. An encyclopaedic report on nutrition and cancer by the World Cancer Research Fund (1997) has confirmed the central importance of diet as a major determinant of many forms of cancer across the globe. The interactions between diet and the biological processes leading to the... 

The major determinant of myocardial redox status is the glutathione content of the heart (Griffith and Meister, 1979). Therefore, fluctuations in myocardial glutathione status may exert a regulatory role in cellular metabolism in a comparable manner to the phosphorylation and dephosphorylation of proteins and enzymes. 

It is known that, while the injury is not manifest until reperfusion with oxygenated solution commences, the duration of the p>eriod of preservation is the major determinant of the extent of the preservation-reperfusion injury. Hence, changes in the liver during the ischaemic period prepare the liver for injury when oxygen is reintroduced. The target of preventive measures should therefore be the ischaemic changes or the events that occur immediately after reperfusion. In the latter case, reactive oxygen free radicals may be involved. 

Nevertheless, numerous QSARs involve other lipophilicity dependencies to model biological activity of drugs, among which Kubinyi s bilinear relationship must be quoted [338] (see Ref 109 for a review). However, the database collected by Hansch s group showed in 1993 [339] that only 15% of the biological QSARs do not imply any lipophilicity term. Hence, lipophilicity is clearly a major determinant of biological activity [340]. 

Major determinants of membrane fluidity may be grouped within two categories [53] (1) intrinsic determinants, i.e., those quantifying the membrane composition and phase behavior, and (2) extrinsic determinants, i.e., environmental factors (Table 1). In general, any manipulation that induces an increase in the molal volume of the lipids, e.g., increase in temperature or increase in the fraction of unsaturated acyl chains, will lead to an increase in membrane fluidity. In addition, several intrinsic and extrinsic factors presented in Table 1 determine the temperature at which the lipid molecules undergo a transition from the gel state to liquid crystalline state, a transition associated with a large increase in bilayer fluidity. 

A basic grasp of normal cardiac function sets the stage for understanding the pathophysiologic processes leading to HF and selecting appropriate therapy for HF. Cardiac output is defined as the volume of blood ejected per unit of time (liters per minute) and is a major determinant of tissue perfusion. Cardiac output is the product of heart rate (HR) and stroke volume (SV) CO = HR x SV. The following describes how each parameter relates to CO. 

Another mechanism to maintain CO when contractility is low is to increase heart rate. This is achieved through sympathetic nervous system (SNS) activation and the agonist effect of norepinephrine on P-adrenergic receptors in the heart. Sympathetic activation also enhances contractility by increasing cytosolic calcium concentrations. SV is relatively fixed in HF, thus HR becomes the major determinant of CO. Although this mechanism increases CO acutely, the chronotropic and inotropic responses to sympathetic activation increase myocardial oxygen demand, worsen underlying ischemia, contribute to proarrhythmia, and further impair both systolic and diastolic function. 

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